[Adding Bjorn, Jordan and John because I really don't want a bunch of
different ways to tell the driver that the firmware is screwing things up]
On Sat, Jul 04, 2020 at 02:28:09PM +0200, Konrad Dybcio wrote:
> This adds the downstream property required to support
> SMMUs on SDM630 and other platforms (the need for it
> most likely depends on firmware configuration).
>
> Signed-off-by: Konrad Dybcio <konradybcio@xxxxxxxxx>
> ---
> .../devicetree/bindings/iommu/arm,smmu.yaml | 10 ++++++++++
> drivers/iommu/arm-smmu.c | 15 +++++++++------
> 2 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> index d7ceb4c34423..9abd6d41a32c 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> @@ -102,6 +102,16 @@ properties:
> access to SMMU configuration registers. In this case non-secure aliases of
> secure registers have to be used during SMMU configuration.
>
> + qcom,skip-init:
> + description: |
> + Disable resetting configuration for all context banks
> + during device reset. This is useful for targets where
> + some context banks are dedicated to other execution
> + environments outside of Linux and those other EEs are
> + programming their own stream match tables, SCTLR, etc.
> + Without setting this option we will trample on their
> + configuration.
It would probably be better to know _which_ context banks we shouldn't
touch, no? Otherwise what happens to the others?
> +
> stream-match-mask:
> $ref: /schemas/types.yaml#/definitions/uint32
> description: |
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 243bc4cb2705..a5c623d4caf9 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1655,13 +1655,16 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
> * Reset stream mapping groups: Initial values mark all SMRn as
> * invalid and all S2CRn as bypass unless overridden.
> */
> - for (i = 0; i < smmu->num_mapping_groups; ++i)
> - arm_smmu_write_sme(smmu, i);
>
> - /* Make sure all context banks are disabled and clear CB_FSR */
> - for (i = 0; i < smmu->num_context_banks; ++i) {
> - arm_smmu_write_context_bank(smmu, i);
> - arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_FSR, ARM_SMMU_FSR_FAULT);
> + if (!of_find_property(smmu->dev->of_node, "qcom,skip-init", NULL)) {
> + for (i = 0; i < smmu->num_mapping_groups; ++i)
> + arm_smmu_write_sme(smmu, i);
> +
> + /* Make sure all context banks are disabled and clear CB_FSR */
> + for (i = 0; i < smmu->num_context_banks; ++i) {
> + arm_smmu_write_context_bank(smmu, i);
> + arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_FSR, ARM_SMMU_FSR_FAULT);
> + }
> }
Do we not need to worry about the SMRs as well?
Will
